Passive swap gate designs for contiguous disk bubble devices

The designs of two novel passive swap gates for contiguous disk devices are described. The data swap is activated by temporary reversal of the drive field rotation direction. Two buffer loops with four merge gates are Combined to form a synchronous swap (true swap) gate. This approach resolves the data overlapping problem and allows flexibility for the matching of the data paths. The structure is sufficiently simple so that it can be used for block swap operation. However, to swap the complete data on the major loop section this arrangement requires two sets of reverse-forward field rotations. For an asychronous block swap operation, a single buffer loop with three merge gates (per swap gate) can be used. Only one set of reverse-forward rotations is required to achieve a complete swap. In this case, the block of data that transfers out is shifted by a fixed bit length.